I realise that I am taking a short cut here (I am not sure about the English terms and am not realy following the book): capacity management can work on 3 levels: services, applications and resources. Especially with applications, there might be a relationship between capacity and release mgt, that could/should go via change management. For every new release, the capacity manager should be given the opportunity (through CAB) to assess any alterations needed due to this change in order to support the new IT infrastructure with enough capacity.

Hello Michiel,
Thank you for the information you provided, I continued me search and I was able to link Release Management to Capacity Management through the 'modeling" activity to simulate infrastructure performance.